1. Field of the Invention
This invention relates to orifice compensated hydrostatic bearings and more particularly to using a roughened surface for reducing the whirl frequency ratio of fluid within the annulus of the orifice compensated hydrostatic bearings.
2. Description of the Related Art
Orifice compensated hydrostatic bearings are very popular but to make them more robust they have a large clearance to radius ratio for reducing rubbing on start up and shut down which increases the bearing life. The increased clearance to radius ratio however permits cross coupling forces to grow which are a rotor destabilizing mechanism. The cross coupling forces are caused by the increased flow of the fluid film within the annulus traveling tangentially with the surface of the rotor, as the fluid moves from the high pressure source to the low pressure sump. The resulting increase in the whirl frequency ratio increases rotor destabilizing forces and reduces the rotor dynamic stability allowances.